Abstract Background: Breast cancer (BC) is the most commonly diagnosed cancer in women. The American Cancer Society (ACS) guidelines recommend annual screening mammography for women of average risk beginning at age 40. Objective: Based on the ACS recommendation, we sought to determine whether women aged 40 years and older who had annual screening mammogram before BC diagnosis incurred lower healthcare costs after BC diagnosis compared to those who did not follow the guidelines. Methods: We used data from a large private health insurance claims database (Thomson Reuters Marketscan Research Databases), 2006-2010. Our sample included women aged at least 40 years with a BC diagnosis between January 2009 and May 2010 and excluded women with cancer other than BC. The study period was chosen to allow for (1) the observation of their screening behavior (3 years) before BC diagnosis and (2) the determination of their metastatic status. A woman was determined to have metastasis upon diagnosis if within the period of 1 month before and 7 months after BC diagnosis, she had at least two metastasis codes and chemotherapy (algorithm adapted from Schootman et al. 2009). The outcome variable was total healthcare costs after BC diagnosis. Costs in MarketScan are defined as adjudicated reimbursement amounts from insurer claims data. Women who had annual mammogram screening (ACS guidelines followers) were defined as women who had a screening mammogram every calendar year from January 2006 until their BC diagnosis. Multivariable regression analyses of log-transformed total costs were conducted, adjusting for age, months between BC diagnosis and December 2010, employee classification (e.g., salary union), employment status, geographic location (e.g., northeast, south, etc.), metastatic status, and whether they received wire localization, lumpectomy, partial mastectomy, radical mastectomy, breast reconstruction, chemotherapy, and radiotherapy. Results: 7,892 women with BC were identified. Among them, 27% had screening mammography every calendar year before their BC diagnosis. In the multivariable analysis, women who had annual mammogram screening were associated with a 4.6% higher cost (p=0.03). Women with metastatic diseases at diagnosis increased healthcare costs by 143.8% (p<.0001). Health care costs increased by 0.9% each month after diagnosis (p<.0001). Wire localization incurred 40.4% higher costs (p<.0001). Lumpectomy increased healthcare costs by 45% (p<.0001). Partial mastectomy was associated with 42.3% more costs (p<.0001). BC patients undergoing radical mastectomy had 34.6% more costs (p<.0001). Breast reconstruction increased costs by 62.6%. Patients who received chemotherapy had 189.8% higher healthcare costs compared to those who did not receive chemotherapy (p<.0001). Radiotherapy was associated with 95.9% more costs (p<.0001). Conclusion: This study provides evidence suggesting that even amongst an insured population, it appears that less than 30% of breast cancer patients had annual mammogram screening before diagnosis and that these patients were associated with higher healthcare costs in the early stage after their BC diagnosis. Future studies need to be conducted to further examine total healthcare costs throughout breast cancer survivors’ life span. Citation Format: Su-Hsin Chang, Lauren T Steward, Bettina F Drake, Sarah Lyons, Susan Kraenzle, Melody S Goodman. Does annual mammogram screening incur lower healthcare costs for breast cancer women after diagnosis? [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-07-16.